Re: [PATCH] x86/irq: Use printk_deferred() on raw_spin_lock() protected sections

From: Joe Perches
Date: Thu Sep 24 2020 - 12:09:04 EST


On Thu, 2020-09-24 at 12:28 +0200, Peter Zijlstra wrote:
> On Mon, Sep 21, 2020 at 06:22:12PM +0200, Daniel Bristot de Oliveira wrote:
> > While testing hotplug I got this BUG:
> > It was caused by printk() inside a code section protected by a
> > raw_spin_lock() that ended up calling a serial console that
> > uses a regular spin_lock().
> >
> > Use the printk_deferred() to avoid calling the serial console
> > in a raw_spin_lock() protected section.
>
> I consider printk_deferred() to be a bug, can't we just wait for the new
> printk implementation to land so we don't need all this nonsense?

It will be good to do a sed fixup for all these
printk_deferred uses soon, but in the meantime
isn't it useful to avoid BUGs?